How to Replace a Treadmill Running Belt and Deck

Replacing a Treadmill Walking Belt and Deck

Over time a treadmill belt stretches and either rips or becomes so long it can no longer be adjusted tight enough to prevent the belt from slipping. 

The same goes with the treadmill deck; Over time the treadmill deck becomes worn and no longer offers a smooth slick surface for the belt. 

When either of these instances occurs, it is time to replace both the belt and the deck.

Here we offer the basics of both belt and deck replacement.

A Basic Guideline for Removing and Replacing a Treadmill Belt and Deck

Due to different brands and designs of treadmills, the following should only be used as a guideline. If any of the information is not exact to the treadmill being serviced, refer to the service manual or call Sportsmith for further help.


Tools needed may vary depending on the treadmill.

  • Phillips Screwdriver
  • Set of Allen Wrenches
  • Set of Box End or Open Face Wrenches


  1. Turn the power switch for the treadmill to the OFF position.
  2. Unplug the power cord from the wall outlet.
  3. Remove the finger guard and/or the end cap retaining screws near the rear roller.
  4. Loosen each rear roller bolt by 10 full turns.  Count the remaining turns necessary to remove the rear roller bolts.  Write down the number of turns needed to remove the bolts on each side of the rear roller for future reference.
  5. Carefully remove the rear roller from the unit.  Clean off any wax or debris buildup from the roller and set it aside.
  6. Remove the front shroud or motor cover and set it aside.
  7. Locate the drive belt on the drive motor.  Work the drive belt off of the motor pulley by hand turning the flywheel while pushing the belt to the side.
  8. Remove the front roller retaining bolts.  (In some cases you may have two bolts.  In this case, refer to the same procedure as the rear roller, count the turns for proper alignment later.)  In some instances, in order to remove the front roller bolts, you will need to unbolt the treadmill frame so that it is able to separate from the console upright arms.  By doing this, you are clearing space to allow the front roller bolts to be removed from the ends of the front roller.
  9. Carefully remove the front roller from the unit.  Clean off any wax or debris buildup from the roller and place it aside.
  10. Loosen and remove the deck mounting hardware.  This may also mean, prying the staples out of the side rail covers and then removing them in order to expose the deck hardware.  Your new belt may have come with hardware meant for use when reattaching the side rail covers.
  11. Remove the deck and the belt by raising the right side edge of the deck over the frame rail and sliding it to the right.
  12. When installing a new belt or deck it is important to note that a new belt and deck should always be installed together. Failure to adhere to this guideline will severely shorten the life of the newly installed parts. Some decks can be used on both sides. However, be sure that each side is used only once. Be sure to install the belt in the proper direction on the unit.
  13. Install the belt and deck by first putting the belt on the deck, and then installing them from the right side as a unit.  Be sure the mounting holes are aligned.
  14. Install the deck mounting hardware and the side rail covers.  If applicable us the new mounting hardware to attach the side rail covers.
  15. Carefully place the front roller on the deck under the belt and push it forward into place, while placing the drive belt on the inside of the drive pulley.
  16. Replace the front roller bolts. If your treadmill has an adjustable front roller, refer back to the number of turns you wrote down previously.  This should help you get close to the proper alignment.  It also may be helpful to install the bolts just a couple of turns and then come back to them after the rear roller is installed.
  17. Once the roller is installed, you can spin the roller by hand while pushing the drive belt onto the pulley.  Be sure to spin the roller several times to ensure complete installation and alignment of the drive belt on the pulley.
  18. Install the rear roller into the unit. Carefully start each bolt by hand, and turn one to two threads without tools to ensure cross-threading does not occur.
  19. Tighten each rear roller bolt the number of turns previously written down, as a reference point.
  20. Install the front shroud or motor cover.
  21. Plugin and turn the power switch to ON.
  22. Start the unit at a very slow speed and check for proper belt alignment. Remember to start at the slowest speed possible and be ready to stop the unit quickly if needed.  If the belt is not moving, make equal turns to each side of the rear roller until it does.
  23. If the belt is moving to the right side of the unit, tighten the right roller bolt. If the belt is moving to the left side of the unit, tighten the left roller bolt until the belt is tracking properly.  CAUTION: Make very small adjustments such as 1/4 turns and then watch the belt for several moments before making another adjustment.
  24. Once the belt is tracking properly, walk on the unit at a slow speed and check for belt slippage. If this is happening, tighten each of the rear roller bolts equal turns until the slippage is no longer occurring. CAUTION: Make very small adjustments such as 1/4 turns and then watch the belt for several moments before making another adjustment.
  25. Increase the unit to a jogging speed to check for belt travel or slippage.  If slippage still occurs, make small adjustments (1/4 turns) to both sides of the rear roller and re-test.
  26. Install the finger guards and/or end caps once you have enough clearance from the rear roller.
  27. Some manufacturers require wax or lube during the install process and the lubricant may be included with your belt.  Apply one packet of lube at the time of install and the second is to be used during your next routine maintenance.

If you have any concerns or need further assistance with replacing your treadmill belt and deck, please contact our experienced tech team at 888.713.2880.

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